Process and apparatus for the electrolytic production of high-purity iron



Jan. 2l, 1964 F. E. SMITH 3,118,826

PRocEss AND APPARATUS FOR THE ELEcTRoLYTIc PRODUCTION 0F HIGH-PURITY IRON AHornegs Jan. 2l, 1964 E. sMrrH PRocEss AND APPARATU S FOR THE ELECTROLYTIC PRODUCTION 0F HIGH-PURITY IRON 3 Sheets-Sheet 2 Filed Sept. 17, 1959 rwrr Jan. 21, 1964 F. E. sMn-H 3,118,826

PRocEss AND APPARATUS Foa THE ELEcTRoLYTTc PRODUCTION oF HTGH-PURTTY IRON Filed Sept. 17, 1959 3 Sheets-$11661'. 3

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AJrJrovneqs United States Fatent ilice 3,ll8,826 Patented Jan. Z1, 1964 3,118,326 PROCESS AND APPARATUS EUR THE 'ELECTR- LYTHI PRODUCTIN F HIGH-RURITY IRON Frank E. Smith, 250 leerson Ave., Niagara Falls, NX. Filed Sept, 17, 1959, Ser. No. 840,712 it Claims. (Cl. 204 113) This invention relates to process and apparatus -for the electrolytic production of high-purity iron.

It is the principal object of the invention to provide a process which enables the production of high-purity iron from low-grade or impure metal, such as pig iron, and at .a cost comparable with present-day production of iron and steel from converters and open hearth lfurnaces.

A further object of the invention is to provide a process of, and apparatus for refining impure iron, to replace open hearth procedures presently used.

Another object is to provide a process and apparatus by which high-purity iron may be produced electrclytically in large quantities through the use of electrodes having flat faces reciprocally varying in thickness during a run so that the pre-set spacing of the faces remains substantially constant.

A still further object is to provide an electrolytic cell p in which circulation of fresh electrolyte across and between confronting faces of the electrodes is even and uniform throughout the length and height of the electrodes.

Another object is to provide an economical and eficient electrolytic cell as aforesaid, in which the electrolyte is cleansed of sediment and impurities, renewed and cooled outside the electrolytic zone, then recirculated across and between electrodes.

Yet another object is to provide a cell construction which enables anode-cathode pairs to be made up before introduction into the cell and then loaded thereinto with a minimum loss of time, so that almot continuous production 'of the cell may be maintained throughout its life.

Another object is to provide a process by which highpurity iron may be produced in lar-ge quantities for the precise control and output of alloys and at costs comparable to those of prior art methods.

Other objects and advantages of the invention will become apparent to those skilled in the art, after a study oi' the following description in connection with the accompanying drawing.

In the drawing:

FIGURE l is a central vertical cross section through one of the cells embodying the invention;

FIGURE 2 is a horizontal cross section taken in a plane identified by line 2 2, FIGURE 1;

FIGURE 3 is a horizontal cross section taken in a plane identified by line 3 3, FIGURE 1, parts being broken away for -greater clarity of illustration;

FIGURE 4 is a detail View to a reduced scale, showing the manner in which the electrodes reciprocally vary in thickness during the operation of a cell;

FIGURE 5 is a vertical cross sectional view taken in a plane identified by line 5 5, FIGURE 6, and showing a modified form of cell construction; and

FIGURE 6 is a vertical cross sectional view taken in a plane identified by line 6 6, FIGURE 5.

Referring in detail to the drawing, 1 identifies a foundation on which rest a plurality of beams 2 in spaced parallel relation and supporting the circular metal bottom plate 3 of the cell. As shown upon FIGURE l, the cylindrical wall 4 of the cell encompasses and extends below bottom plate 3 to rest upon a metal ring '5, so that the weight of the cell wall and parts carried there-by is transmitted directly to the foundation.

The metallic bottom and walls of the cell are protected by a lining 6, of concrete. A horizontal partition generally indicated at 7 is conveniently cast integral with lining 6 to provide a planar upper face. The partition is reenforced by `a pair of I-beams 8 and 9 extending between opposite portions of the side wall, in spaced parallel relation and equally spaced from and upon opposite sides of their parallel diameter. These beams are ernbedded in concrete trusses which, as shown upon FIG- URE l, are shaped to provide spaced parallel confronting ledges 7a. land 7b, defining between them a central diametral opening for `circulation of Ithe electrolyte as subsequently described. As best shown upon FIGURE 3, the two segment-shaped portions oi the partition are provided, respectively, with rectangular openings 10 and 11 to provide return circulation of the electrolyte. Re enforced, spaced, parallel beams 12 and '13 at the top of the tank are conveniently cast integral with it. Each is directly over a corresponding one of the reen'forcements 8 and 9, with their top surfaces coplanar with the top rim of the tank. This rim includes an angle ring 14 welded or riveted ilush with lthe top edge of the tank wall. A llat circular cover 1S of concrete has a central opening 16 disposed over the corresponding opening -in partition 7. Opening 16 is sized for convenient insertion and removal of the electrode pairs.

A removable superstructure `generally identified at 17, FIGURE l, rests upon cover 15 over opening 16 and protects the bus bars subsequently described. This superstructure which may be of wood includes parallel side walls 18 and 19 connected by arcuate end walls Ztl and 21 and a top 22, provided with an inspection opening 23 4and a hinged lid 24. As best shown upon FIGURE 2, the end walls 20 and 21 follow the curvature of top or cover 15 and have openings such as 25, 26, FIGURE 2, for bus bars 27, 28 which for convenience will be taken `as positive and negative, respectively. Where a number of these `cell units are in side-by-side position, the bus bars may -run from one to the next, as indicated at 27a, FIGURE 2. Each bus bar is shown to consist of a pair of copper straps supported at each end by insulators 29 and 3d mounted on cover 15 and having upstanding projections between land iixed to the straps. A switch 28a is open when the cell is operating and closed to cut it oil the line.

FIGURES l and 3 show anode A and cathode C `as they exist at the beginning of a run or cycle. The anode consists of a slab of impure iron to be refined, such as pig iron, and may be twelve inches or more in thickness, while the cathode consists of a relatively thin slab of high-purity iron. From FIGURES l and 3 it will be noted that anode 4and cathode have the same dimensions in the vertical direction and in the horizontal direction parallel with the bus bars. It will also be noted that the electrodes are supported on and along the respective ledges '7a and 7b of partition 7, with small overlap at their ends. Thus they are supported in erect position over the central opening in the partition, with their confronting faces parallel and closely spaced by from one and one-half to one-quarter of an inch as determined by conditions subsequently explained. There is -thus deiined between the electrodes a uniform iiow space 3i for electrolyte E.

Each electrode has welded to its back vertical surface, a plurality of yokes 32. Comparing FGURES 1 and 2, it will be noted that each electrode is provided with four vertical rows of these yokes evenly spaced in the horizontal direction, each row comprising a vertical column or series of four yokes, also uniformly spaced. A ribbon or strap of copper, such as 33, extends from the level of the bus bars, downwardly through each respective vertical column of yokes and is held in flat contact with its electrode by set screws 34 threaded into and through the yokes. Two set screws are shown for each yoke. See FGURE 3. In this Way a precise and uniform distribution of current is effected over the faces of the electrodes. Each strap 33 is protected from stray currents by a covering of insulating paint except over its contact and confronting face areas, and is connected with its bus by Z-connectors such as 35 and 36. Thus, for example, each anode strap 33 has a connector 3' with one offset end fixed thereto and its other end attached to the respective bus bar. The connectors 36 between cathode bus bar 2S and its drop copper are essentially like those described for the anode but are shorter than connectors 35 because of the closer proximity of bus 28 to the contiguous edge of opening 16. To reduce by-passing of current, a sheath 33a of insulating or dielectric material such as micarta or asbestos board, is provided to contact or rest upon the electrodes and to extend to a level a little above the highest level attained by the electrolyte during a cycle of operation. Conveniently this sheath may be in the form of a unitary insert or as separable sheets. In either event, as shown upon FIGURE 3, its ends project beyond its sides into substantial contact with abutments 6a of the tank lining to be thereby held in iixed position. Also, as shown in FIGURE 6, end plates 33b extend downwardly over the entire end areas of the electrodes to thereby close the electrode Zone from stray currents.

The partition 7 generally divides the tank into cornmunicating upper and lower compartments. The upper compartment is, in turn, divided into three distinct chambers or sections, by removable panels 57 and 38 extending vertically between beams 12 and 13, respectively, and partition 7. Thus, referring to FIGURE l, panel 37 has a Z-bar 39 secured to and along its upper edge to tit smoothly about the adjacent corner of beam 12. The lower edge of the panel has an angle bar 4h lixed therealong to rest upon the partition. Thus the panel with its bars may be removed by sliding it inwardly and upwardly. The panel 38 at the cathode side of the cell is essentially an allochiral duplicate of panel 37, so that it is sufficient to identify angle bars 41 and 42 secured to and along the upper and lower edges, respectively, of the panel. Alternatively, the panels 37 and 3S alone may be removable, with angles such as 39 and 46 iixed in position. In either case the panels divide the upper compartment of the tank into three sections, namely, a central or electrode section and two segmental-shaped sections on either side of the central section which, as subsequently explained, are for the conditioning of the electrolyte.

Circulating pumps 4S and 44 are mounted on opposite sides of cover 15'. Pump 43 is provided with driving motor 45, intake pipe 46 extending downwardly into the left chamber or section, as the parts are viewed upon FIGURE 1, and discharge pipe 47 extending into the central chamber or section. Since the two pump units are preferably duplicates, it is suflicient, referring to pump 44, to identify its driving motor 48, intake pipe 49 and discharge pipe 50. From FIGURE 2 it is noted that the discharge pipes 47 and 5t? enter the central section at discrete locations spaced therealong to assure an even tlow and supply of fresh electrolyte.

As indicated by the arrows of FIGURE l, operation of the pumps induces flow of electrolyte downwardly through the central section, across and between the confronting faces of the electrodes, thence upwardly through openings E@ and il in partition 7, back to the side sections previously identified. Cooling coils 51 and 52 are positioned just above the openings and are connected with a source of coolant, circulating and control means, not shown. The circulation of coolant may be under control of valves, not shown, thermostatically operated in response to small temperature changes of the electrolyte, to effect a close and precise control of temperature. Such valves, which are well known in the art, are settable for any selected value over a suitable range of temperatures.

Two baskets or containers 53 and 54 having grilled or foraminous sides and bottoms are shaped to correspond with openings 1G and 11, respectively, and sized to rest upon the edges thereof, as will be clear from inspection of FEGURES l and 3. For a purpose to be subsequently described, these baskets are iilled with iinely divided steel and are easily removable for that purpose.

The lower portion of the tank or cell forms a settling chamber for sludge released from the anode. To remove this sludge as conditions require during a cycle of operation, I provide a screw conveyor 5S extending diametrically across the bottom of the tank and driven, in a way obvious from inspection of FIGUE l, by a belt 57 and motor S6 mounted upon a bracket 5S fixed to one of a plurality of vertical reenforcing beams 59. As shown upon FGURE 3 there are six of these beams at equallyspaced intervals about the periphery of the tank. Each beam rests upon ring 5 and extends upwardly to a level short of the top of the tank. The sludge is discharged through a downspout 6i? under control of a valve 61.

Coils 62 are provided near the bottom of the lower chamber and connected with a source of heating medium and control valves, not shown, so that the electrolyte may be maintained at optimum operating temperature during change-over, repairs or adjustments, and also quickly brought to operating temperature when first being placed on the line or after a considerable period of shut-down. Electrically-energized heating coils or means may be substituted for coils 62. As indicated at 63, FIGURE l. the bottom of the tank is formed of two half-sections sloping upwardly from a common diametral line defined by conveyor 55. That is, the bottom of the tank is V- shaped in cross section in a vertical plane normal to the plane of FIGURE 1, so that impurities settling out from the anode, gravitate to the conveyor. At 64 there is shown a pipe by which electrolyte may be drawn down to about the level indicated at 65 when the cell is to be charged with new electrodes.

In the modied construction shown upon FIGURES 5 and 6, the draw-down pipe 64 and its associated pumping mechanism, not shown, are not required. In the form of the invention shown in these figures the tank 4 and concrete lining may be in the same form as shown upon lilGURES 1 to 3. However, in the modification being described, ledges 7a and 7b of partition 7 are omitted.

A removable support or cage for the electrodes consists of a base 66 of concrete of open rectangular shape with internal dimensions about the same as those of the central opening in partition 7 and provided with reenforcing channels 6'7 and 68 in its side members. These side members are integrally connected by uniformly-spaced cross bars 69 having their upper edges beveled as indicated at 69a, FIGURE 6, and reenforced by channels 7), to define circulating ports between them.

A plurality of lifting straps 71 are provided, three being used on each side in the model illustrated. Each strap may be welded or otherwise rigidly attached to the lat base of its channel, to extend upwardly to a level above the electrodes A and C which rest upon and are supported by base 66. Referring to FIGURE 6, it will be noted atlassen that each strap il has a lifting eye 72 in its top end. rihe straps are uniformly spaced in parallel vertical positions along each side of the 'oase and are so located that each lies between and in oifset relation with two adjacent copper lead-ins 33, as described in connection with FIG- URES l, 2 and 3. It will be understood that these leads may be connected with the electrodes in the manner previously described.

With the modified construction, a frame 66 may be loaded with a pair of electrodes outside the tank then lifted by a crane by means of straps 71 and positioned within the tank, with base 66 resting upon partition 7, as depicted upon FIGURE 5.

Ey the use of the construction shown upon FIGURES 5 and 6, it is possible to maintain a cell in almost continuous production since only a few minutes are required to withdraw a pair of electrodes, that is, an eroded anode and a full cathode of high-purity iron, instal a new pair as in FIGURES l and 5 and start a new cycle of production.

peralz'on in operation a unit is loaded with an anode in the form of a relatively thick slab of iron to be refined, such as pig iron. These slabs may be cast directly from a blast furnace. At the start the anode may, in the form shown, have a thickness of a foot or more. The cathode is a slab of high-purity iron having a thickness of about one inch. The flat parallel confronting faces of the electrodes may have a spacing of from one-quarter to one and one-half inches, depending upon the smoothness of the electrode faces. That is to say, the spacing will be a minimum where the confronting faces are smooth, and greater with increasing roughness or irregularities of these faces.

The electrolyte is an aqueous solution of ferrous chloride having a concentration of from l to 8 pounds per ten pounds of water and a pH of between 5 and 8. By the control of iiuid to and through coils Si and 52, the temperature is maintained between 65 and 80 C. The current density may have any value between l and 6 amperes per square inch. However, since the time required for a cycle will be in inverse proportion to the current density, the maximum practical density is prefcrred.

The voltage for operation is as follows.

Volts To convert Fe++ to Fe +0.441 To convert Cl* to Cl atom +1358 Total 1.799

Bath resistance (approximate):

1A" spacing +0.40 l spacing +1.50 ll/'z" spacing +2.25

Bath resistance varies with the current density that is, amperes per square inch per inch. As an example, 1'. x 0.25 ohm x 6 amperes/sq. in. resistivity of the bath per square inch per inch of length.

The pumps t4 and 45 are selected to induce a flow between electrodes of from 5 to 40 feet per minute. Due to the relatively large capacity of the pumps and the spacing of their discharge pipes in and along the elecrode chamber, a smooth and uniform ow between electrodes is continuously maintained, thereby assisting in an even erosion of the anode face and a corresponding uniform accretion of high-purity iron at the cathode. This function is enhanced by the fact that the level of electrolyte over the electrodes is maintained a substantial distance above them so that turbulence of liquid ilow between them is negligible.

As indicated by the arrows upon FIGURE 1, the ow of electrolyte is downwardly between electrode faces, through the central opening in partition '7, to the lower CTI chamber. In this chamber the ilow divides, half of the electrolyte moving upwardly through opening 10 and half through opening 11. Due to the much greater ow area provided as the electrolyte emerges downwardly from the central electrode chamber, its velocity decreases to provide plenty of time for impurities to settle to the bottom of the tank. This function is augmented by the change to an upward direction of flow as the electrolyte begins to move upwardly to the side sections of the upper chamber.

During its passage between electrodes, the electrolyte provides a continuously renewed solution of ferrous chloride. At the same time it acts to maintain a uniform temperature of the electrodes and to wash down impurities released from the anode as it is gradually eroded.

As the electrolyte passes into the electrode zone, the ferrous ions (Fe++) migrates to the cathode and the chlorine ions (Ch) migrate to the anode. As the ferrous ions contact the cathode and lose their charge, they become a part thereof. The chlorine ions, in contacting the anode are converted to atomic chlorine and immediately react with the iron or the anode to form more ferrous chloride, so that the concentration of ferrous chloride is maintained. Any ferrie chloride in the solution is converted to ferrous form as the electrolyte moves upwardly through the mass of finely divided steel in baskets 53 and 54, as previously described.

As the anode is eroded the impurities therein are washed downwardly by the continuous even flow of electrolyte across and between the electrode faces and settle to the bottom of the tank where they are removed by conveyor 55. The conveyor may be run intermittently or continuously as conditions and rate of production require.

A very close control of temperature within the range previously specified, is afforded by coils 5l and 52 because the electrolyte is continuously recirculated over and about them at a greatly reduced velocity over that between electrodes. Ample time is thereby aiforded for heat exchange from the electrolyte to the coolant in the coils. Since cooling is effected after the solution has passed through the finely divided steel in baskets 53 and 54, a maximum rate of conversion of ferric to ferrous chloride is assurred.

In the form of electrode supportinfy means shown upon FIGURES 5 and 6, anode-cathode pairs, together with their pallet 66 are made up in advance, ready for insertion into a cell. Reloading of a cell may be effected in a matter of minutes so that each cell may be kept in production substantially continuously. The high-purity iron of the cathode is essentially free of sulphur, manganese, phosphorous, iron oxides, carbon, silica and gases such as hydrogen and nitrogen. Being highly resistant to atmospheric corrosion, it finds many uses as it comes from the cell, for example in water piping, screens, railings and fences. It is a superior product for transformer cores, motors and electronic applications. The high-purity iron produced by my invention may be used for containers, without tin plating, for non-acid substances such as oil; and it can be produced at lower cost than the tin plate conventionally used for such materials. It is a superior material for automobile bodies because corrosion will not occur under the finish nor on the inside surfaces, so that undercoating is not required. Furthermore, it is superior as a base for chromium plating since it avoids the penetration of rust commonly encountered at present.

FIGURE 4 shows the electrodes as they exist When a run is about half completed and it will be noted that the spacing between the electrodes remains substantially constant throughout the run. This is important because it enables the conditions of voltage, current density, temperature and rate of circulation of electrolyte to be maintained uniform or varied in a precise predetermined way during the run, thus resulting in a high-purity iron uniform in composition for alloying with carbon, nickel,

chromium, molybdenum, tungsten and other known elements and compositions. Since the slabs produced are extremely pure, a very close and precise control in the production of alloy steels is possible. Alloys so produced are superior to those produced by the vacuum melting rocess currently used.

While I have disclosed the form of process and apparatus presently preferred by me, numerous modifications and substitutions of equivalents are possible and will occur to those skilled in the art after a study of the foregoing disclosure. For example, I may substitute a bath of ferrous bromide for the ferrous chloride bath previously described, and in about the same concentration. Or, alternatively, I may use ferrous bromide as an additive to the ferrous chloride, in the ratio of about four pounds of FeCl2 plus three pounds of FeBr2 to ten pounds of water. In cases where, due to inadvertence or lack of proper control of the variables of temperature, rate of circulation of the electrolyte and current density, the :anode face becomes rough, uneven or pitted, it will be withdrawn from the bath and reconditioned by grinding or machining its face to restore it to clean smooth face. Of course such a procedure need not delay production since a new pair of electrodes may be inserted into the cell in a few moments and the used ones smoothed and later replaced into the cell. Therefore, this disclosure should be taken in :an illustrative rather than a limiting sense; and it is my desire and Aintention to reserve all modifications of process and apparatus within the Scope of the subjoined claims.

Having now fully disclosed the invention, what I claim and desire to secure by Letters Patent is:

l. A method of purifying impure iron that comprises establishing an electrolytic Zone of optimum temperature between 65 and 80 C. between electrodes having submerged broad equidistant confronting faces of which the anode is impure iron, flowing ferrous chloride aqueous solution at substantially uniform concentration and about neutral pH, continuously and at substantially uniform velocity of several linear feet per minute uniformly over the said submerged faces of both the electrodes, passing direct current through the flowing solution between the electrodes thereby depositing pure metallic iron at the cathode, and releasing chlorine on the anode with the formation of ferrous and ferrie salts in the flowing solution, maintaining the velocity of electrolytic flow high enough to clean the faces of the electrodes of loose matter, removing suspended matter from the used electrolyte, reducing the newly-formed ferrie iron salts to ferrous salts in the flowing solution by passage over divided iron thus increasing its ferrous iron concentration, adjusting the temperature of the solution to optimum electrolytic temperature, and returning the solution to the electrolytic zone.

2. A method of producing substantially pure iron cornprising circulating yan aqueous solution of ferrous chloride at a concentration of about l to 8 pounds per ten pounds of water, at a pH about 5 to 8, at a speed of about 5 to 40 linear feet per minute, downward between an initially large, wholly submerged anode of relatively impure iron, and an initially small, wholly submerged electrode of relatively pure iron, which are uniformly separated by about 1/4" to 11/2, flowing the solution after leaving the electrodes to a sump and reversing the direction of flow thereby assisting in the precipitation of solids, flowing the solution from the sump upward and through finely divided iron and thereby reducing ferrie chloride to ferrous chloride, returning the solution from the reduction of the ferrie salt to a position above the electrodes, supplying direct current of about 3.2 to 4.5 volts and a current density of l to 6 amperes per square inch to the electrodes and maintaining the temperature of the electrolyte above the electrodes at about 65 to 80 C.

3. A method of producing substantially pure iron comprising, circulating an aqueous solution of ferrous chloride at a concentration of about l to 8 pounds per 10 pounds of water, at a pH of about 5 to 8, at a speed of about 5 to 40 linear feet per minute, vertically between an initially large, wholly submerged anode of relatively impure iron and an initially small, Wholly submerged electrode of relatively pure iron, which are uniformly separated by about 1A to 11/2, adjusting the temperature of the solution after the electrolysis and reducing ferric chloride in the solution to ferrous chloride, returning the solution from the reduction of ferrie salt to the electrolysis above the electrodes at the preferred temperrature for electroylsis, and supplying direct current of about 3.2 to 4.5 volts and a current density of 1 to 6 amperes per square inch to the electrodes.

4. A method of producing substantially pure iron comprising, circulating an aqueous solution of ferrous chloride at a concentration of about l to 8 pounds per l0 pounds of water at a pH of about 5 to 8 and at a speed of about 5 to 40 linear feet per minute, between a wholly submerged anode of relatively impure iron and a wholly submerged electrode of relatively pure iron countercurrent to the convection currents generated in the solution by the heating effect of the electrodes, reducing ferric chloride in the solution issuing from the electrodes to ferrous chloride, returning the solution from the reduction of the ferrie salt to the electrolysis, supplying direct current of about 3.2 to 4.5 volts and a current density of l to 6 amperes per square inch to the electrodes, and maintaining the temperature of the solution at the place of electrolysis at about 65 to 80 C.

5. A method of purifying impure iron that comprises flowing a current of electrolyte of ferrous chloride from end to end over the whole surface of an impure iron anode and of another electrode, passing an electrolytic direct current with a current density of about l to 6 amperes per square inch, at a temperature between about 65 to 80 C., between the electrodes at a minimum velocity of about 5 linear feet per minute and sufficient to clean the electrodes of loose matter, reducing ferrie chloride salts in the electrolyte to ferrous chloride, adjusting the temperature of the electrolyte to the electrolytic opearting temperature, and returning the electrolyte to the electrolytic zone.

6. A process of electrolytically purifying iron that comprises flowing an electrolyte containing a ferrous halide between electrodes, of which the anode is low grade iron, at a pH of 5-8, at uniform velocity of several linear feet per minute over the whole submerged faces of uniformly spaced electrodes, and thereby simultaneously depositing high grade iron from solution upon the cathode and dissolving iron from the anode as iron halide, reducing ferrie halide salts in the used electrolyte to ferrous halide in a reduction zone remote from the electrolytic zone, and adjusting the temperature of and returning the electrolyte to the electrolytic zone at a temperature of about 65 to 80 C. to complete the cycle.

7. A method of purifying iron that comprises flowing an electrolyte at a temperature about 65 to 80 C. containing ferrous bromide at a pH about S-8 at a velocity of about 5-40 ft./ min. between equally spaced electrodes, of which the anode is low grade iron, so as to continuously sweep the faces of both electrodes, passing electric current between the electrodes through the flowing electrolyte thereby dissolving iron as containing ferrie bromide from the low grade electrode, and depositing pure iron upon the other electrode, reducing the newly dissolved ferric bromide, and cooling and returning the reduced solution to tbe electrodes.

8. A method of purifying iron by electrolysis that comprises flowing an electrolyte containing essentially ferrous chloride at a velocity of 5-40 ft./min. parallel to the faces of and between opposed electrodes having broad parallel faces spaced apart about 1A to 11/2 inches, of which the anode is low grade iron, passing direct current between the electrodes at a current density between References Cited in the le of this patent UNITED STATES PATENTS Johnson Jan. 17, 1905 Greenawalt Sept. 28, 1920 Schwiete Feb. 13, 1923 Morrison Nov. 3, 1931 Cain Jan. 30, 1934 Trask Ian. 23, 1951 Cunningham Sept. 16, 1958 

6. A PROCESS OF ELECTROLYTICALLY PURIFYING IRON THAT COMPRISES FLOWING AN ELECTROLYTE CONTAINING A FERROUS HALIDE BETWEEN ELECTRODES, OF WHICH THE ANODE IS LOW GRADE IRON, AT A PH OF 5-8, AT UNIFORM VELOCITY OF SEVERAL LINEAR FEET PER MINUTE OVER THE WHOLE SUBMERGED FACES OF UNIFORMLY SPACED ELECTRODES, AND THEREBY SIMULTANEOUSLY DEPOSTING HIGH GRADE IRON FROM SOLUTION UPON THE CATHODE AND DISSOLVING IRON FROM THE ANODE AS IRON HALIDE, REDUCING FERRIC HALIDE SALTS IN THE USED ELECTROLYTE 